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Impact of Space Environmental Factors on Microtechnologies 81

high voltage and power efficiency, collect electrons from plasma, accumulating a
substantial negative charge. To prevent the highly polarized station from
losing large amounts of current, a plasma contactor generates a local high-density
plasma to contact the ambient plasma, maintaining the system electric potential
18
at zero.
AO exists in significant amounts around low-Earth orbits and around Mars.
AO is highly reactive and will react differently depending on the nature of the
materials involved. AO effects were first detected during shuttle missions. Exposure
to AO tends to cause metals to develop an oxide on their surface and polymers to
lose mass and undergo a change in surface morphology. Due to their high reactiv-
ities with AO, polymers and other composites need to be protected. On an order of
magnitude of scale, surfaces such as the solar arrays will be exposed to a stronger
7
AO flux field than inboard components. The LEO range for AO exposure is 10 to
3
8
10 atoms/cm . Exposure to AO is a known detriment to Kapton 1 (DuPont High
Performance Materials, Circleville, OH) wire as AO reduces the thickness of
insulation materials and degrades their insulating properties. A thin, protective
coating of silicon oxide is often used on Kapton solar array substrates for protection
against AO threats.

4.5 CONCLUSION

This chapter is cursory and of an introductory nature giving merely an overview
rather that handling any topic in depth. The consideration of inserting MEMS and
microstructures in critical space flight programs must include the potential stresses
that the piece, part, or component will be exposed to and each of their respective
impact on the long-term survivability of the subsystem. In the reliability portion of
this book there is a greater discussion on the combinations of stress factors from the
various potential environments.

4.6 MILITARY SPECIFICATIONS AND STANDARDS REFERENCED

MIL-PFR-19500 General Specification for Semiconductors
MIL-M-38510 General Specification for Microelectronic Devices
MIL-STD-202 Test Methods for Electronic and E1ectrical Component Parts
MIL-STD-338 Electronic Design Reliability Handbook
MIL-STD-750 Test Methods for Semiconductor Devices
MIL-STD-883 Test Methods for Microelectronic Devices
MIL-STD-975 NASA Standard Electrical, Electronic, and Electromechanical
(EEE) Parts List
MIL-STD-1540 (USAF) Test Requirements for Space Vehicles
MIL-STD-1541 (USAF) Electromagnetic Compatibility Requirements for Space
Systems
FED-STD-209 Clean Room and Work Station Requirements, Controlled Environ-
ment

© 2006 by Taylor & Francis Group, LLC